An image forming apparatus includes a main memory device, an auxiliary storage device, a print request receiving unit, and a print processing unit. The print request receiving unit is configured to (a) receive from an external device a print request that includes the number of printing pages and print image data, (b) select one of the main memory device and the auxiliary storage device as a device to which the print image data is to be written on the basis of the number of printing pages, and (c) write the print image data in the selected main memory device or auxiliary storage device. The print processing unit is configured to read the print image data from the main memory device or the auxiliary storage device and perform a print process based on the print image data.